CA1310261C

CA1310261C - Method and apparatus for repairing casings and the like

Info

Publication number: CA1310261C
Application number: CA000588166A
Authority: CA
Inventors: Charles H. Koster
Original assignee: Nu-Bore Systems
Current assignee: Nu-Bore Systems
Priority date: 1988-01-15
Filing date: 1989-01-13
Publication date: 1992-11-17
Anticipated expiration: 2009-11-17
Also published as: US4865127A; EP0357711A4; EP0357711A1; WO1989006738A1; AU2942389A

Abstract

ABSTRACT OF THE INVENTION

The invention relates to a method and apparatus for relining bores such as oil wells, using multiple layers of spiral wrapped, resilient lining material which expands to form a continuous liner for the bore.

Description

131~2~

BACKGROUND _F TH~ INVENTION

Unclerground bores such as oil wells, pipelines, gas mains and the like are susceptible to cracking or rupturing due to corrosion of the e~isting casings, shifts in the ground and external pressures which can crush or rupture the bores. These losses of integrity can cause the fluids passing through them to seep into the environment which can cause contamination to ~ater tables as well as presenting fire hazards in the cases of gas mains and the like.
Likewise, certain situations re~uire the closure of previous perforations or other man-made openings in casings, tubings or the like. In some cases repairs are re~uired to bores that have been damaged by wear or abrasion by moving components. Al~o, the relining of a bore to present a different material interface within the bore can be extremely advantageous.
To repair these bores various elaborate methods have been developed which generally involve inserting a new seckion 20 of pipe or liner into the bore to be repaired and placing the new lining in the appropriate section and then expanding the lining so that it then fills or covers the gap. These methods for repairing the casin~s generally have been limited to fairly small areas because of the difficulties encountered in handling long liners, and have laryely ~een unsuccessful due to the problem of "springback" of metallic tubular materials when expanded internally. Springback prevents establishment o~ a good seal against the well casing.
SUMMARY OF THE INVENTION
__ In one aspect, the invention resides in a method ~or lining bores comprising, spiral wrapping a plurality of layers . ~? ~

~ 3 1 0 2 6 l 60538~1042 of resiltent strip form lining material about a hollow mandrel and mechanioally securing said material to said mandrel at the ends of said spiral wrapping; inserting said mandrel and lining material into a bore to be relined unwrapping said material from said mandrel so that said material expands until in contact with the bore creating a lininy for said bore; and removing said mandrel.
It is desirable for one of the alterna~ing layers of material to be comprised of a settable resinous material such as an epoxy to ensure adhesion and a complete seal between the various layers of lining materials.
Once the lining material is in place, the mandrel is then withdrawn and the bore is returned to use.
In a further aspect, the invention resides in a mandrel for repairing a bore comprising: a lower packer assembly having a diameter less than said bore capable o~
expanding in size to the diameter of said boret a mandrel connected to one end of said lower packer assembly having a diameter of less than the diameter of said bore; an upper packer assembly having a diameter less than the diameter of said bore, said upper packer assembly being expandable to a diameter equal to the diameter of said bore; means for expanding said lower packer assembly prior to the ti~e when said upper packer assembly is expanded; and a lockin~ assembly between said lower packer asse~bly and said mandrel such that when unlocked~ said lockiny assembly permits said mandrel and upper packer assembly to rotate independent of said lower packer assembly.
By the ~,erm "bore" it is meant any cylindrical opening or the li.ke within a surface to include oil wells, water malns, cJas mai.ns, pipelines, electrical conduits or the ~31 ~2~ 6053~-1042 like.
By "lining materi.al" it is meant any form of flexible material haviny sufficient resiliency or elasticity to uncoil in the manner described. This material can be various sheet metal such as steel having a thickness of between 0.004 inches and 0.030 inches with a preferable thickness o~ 0.010 inches or dictated by the bore to be repaired. For example, for oil wells the use of beryllium copper is preferred because of its corrosion resistance and high strength. In other cases, various plastics reinforeed with glass fiber or carbon fiber, etc. may be employed. Special stainless steels and nickel-base alloys may be of use. It is to be borne in mind that the interior of an oil well is a hostile 2a 2 ~ 1 environment containing chloride~, hydrocarbons, om~times sul-fides, etc. Many metallic materials simply disintegrate i~ such an environment. Beryllium GOpper~ such a~ Alloy 190, having a yield strength o~ about 100,000 to about 125,000 psi and a modulus of 1 5 x 10~ is particularly well suited to the service.

BRIEF DESCRIPTION OF THE DRA~INGS

FIGU~E 1 shows a machine for wrapping lining material about the downhole tool at the well head.

FIGURE 2 shows the tool when it i8 first placed into the : 10 bore.

: FIGU~E 3 hows the lower packer assem~ly in its inflated position with the lining ~aterial unwrapp~d up to the upper : packer.

~ . ~
FIGURES 4 and 5 show, in cross sec~:ion, the lower packer assembly.

FIGURES 6 and 7 ~how, in cross section, of the upper packer : assembly.

EIGURE 8 depicts the arrangement o~ the wrapping material strip at the initiation of the wrapping operation.
.~
FIGURE 9 depicts the thin sheet material which may be formed into a collar about the downhole tool to fasten the wrapping matexial thereto, and FIGURES 10 and 11 depict the sheet of FIGURE
9 after it has been wrapped into a collar.

FIGURES 12A through 12E depict a supplemental ~;a~ety device ~or preventing undesired loss of the tool down the we.ll.

~3~2~11 DETAILED DESCRIPTION OF THE_INVENTION

In carrying the invention into practice, the downhole tsol is first ~repared. The tool comprises an upper packer assembly, a lower packer assembly, which incorporates a release device such as ashear pin operable from the surface to permit rotation of the upper packer with respect to the lower packer upon deman, with the two packer assemblies being spaced apart by a mandrel section of desired length having in mind the 1ength of patch to be effected in the well to be repaired. The mandrel section itself may be made of sections of hol low steel such as tubing steel screwed together to form the requisite length. Each of the pa-cker assemblies has a hollow core, with a check valve being provided at the lower end of the lower packer assembly. The downhole tool is suspended in the well on hollow tubing string steel, permitting transmission of hydraulic eommands to the tool from the surface.

The completed down"ol~ to~ol with spirally~wrapped strip material therearound is depicted in Figure 2 of the drawing as ~ being suspended in a well adjacent a failed place in the well ; casing to be patched. As shown in Figure 2, the tool comprises a mandrel 4 having a lower packer assembly 2 and an upper packer assembly 5. Lining material 2l is shown wrapped about the mandrel in Figure 2. A centralizer 56 may be employed at the bottom end of the tool. The tool is shown suspended from tubing string 3.
Other essential features of the downhole tool include circulating means for fluids which are controlled by commands from the sur-face. These will be described in connection with Figures 4 through 7.

Turning now to Figure 1, which depicts a machine 11 mounted on the well head of a well to be patched in accordance with the invention1 it wlll be seen that the machlne consists of a frame 12 bearing a flxed crosshead 13 and a movable crosshead 14. The movable crosshead is raised and lowered by lead screw 23 which is powered by reversible power head 16 through pins 26. Upper and ~ 3~2~1 lower collets, desiynated 28 and 24 respectively, are mounted on the frame about upper port 17 and on movable crosshead 14.
Collets 24 and 28 are preferahly of the type which are normally closed and require actuation to be opened. Material payoff assembly 27 is preferably mounted concentrically about lead screw 23 and is powered by the same power head 16 which powers lead screw 23. Material payoff means 27 bears a plurality of axles 15 adapted to hold spools of strip 30. Brake means 19 prevents rotation of material payoff means 27 when the movable crosshead 14 is being raised. For this purpose also, dri.ve means 16 is connected to materi~l payoff means 27 by ratchet means so that material payoff means 27 is powered only when lead screw 23 is descending. Upper and lower ports 17 and 18 in the frame are aligned so that tool 22 can be passed completely therethrough. The collects 2~ and 28 are controlled su~h that at leas~ one of them is always closed to grip the ~ool while the wrapping operation is in progress.
To initia~e the wrapping operation, tool 22 is passed downwardly through machine 11 to the point at which the lower packex assembly 2 reaches the wrapping area, i.e., the area at which the strip material 21 wound on spools 30 can reach tool 22 at the angle preset by the axles 15 on which spools 30 are ; mounted. The strip material is fastened to tool 22 over the lower packer assembly 2 r preferably in the pattern depicted in Figure 8 and preferably using the collar device 34 shown on Figure 10 to fasten the strip material to tool 22. At this point, the movable crosshead 14 is in the fully raised position with collet 28 closecl. Collet 24 is then closed and collet 28 is openecl. Power head 16 then moves tool 22 downward while wrapping strip material 21 thereabout. Movement of the tool downward and the rate of rotation of the material payoff ~, L~ ,ip'~

~3~2~

assembly 27 are fixed and coordinated by the pitch of lead screw 23. When the movable crosshead 14 reaches the lower end of its travel, upper collet 28 is closed, lower collet 24 is opened and brake 19 is set so that the wrapped-on strip material 21 will not become unwrapped during the elevation 5a J;.~ J.,~

~3~2g~
of crosshead 14. Crosshead 14 is then elevated by rever~ing power head 16, while no power is transmitted to material payoff mea~s 27 due to the fact that the drive thereto is ratcheted. The process o~ alternately raising and lowering cro~shead 14 to feed and wrap portions of tool 22 is continued until the upper packer as~embly 5 is reached and wrapped. A collar similar to that shown in Figure 10 is then wrapped about the upper pack~r assembly 5 to lock the wrapped strip thereto. rhe strip material is then cut of~ and the tool 22 is ready for use. Sinca there is no longer any need for the machine to remain at the wellhead, and in fact, it can be transported to the next job, tool 22 can be lower~d completely through the wrapping area, fitted with a split collar as a stop.on the wellhead to permit removal of the machine, and the process of patching the well can proceed, Before proceeding with a discussion of the well patching procedure, the construction o~ the upper and lower packer assem-blies will be described with reference to Figures 4 and 5 lLower) and Figures 6 and 7 (Upper) packer assemblies, respectively.
These Ficlures illustrate that the essential ~eatures of the respective packer assemblies are: l) Expandable means (the packers) at the upper and lower ends of the tool permitting expan-sion from the tool diameter to fit ~orcibly against the well casing, 2) Spindle means preferably located adjacent the lower packer assembly which on command can permit rotation of the mandrel and upper packer assembly with respect to the lower packer assembly, and 3) Valve means permitting controlled circulation of fluid under pressure along the inside face of the nawly formed well liner.

Figures 4 and 5 illustrate the uppar and lower portions of the lower packer assembly, with reference character ~4 rapre-senting the steel body of the assembly, 51 representing the packer itself, and being an in~latable rubber sleeve fastaned at the ends to the assembly body 64, re~erence character 50 representing the spindle held together ~rom rotation by shear pin 53, rollers 54 2 ~ ~

which rotate in race 65 after the shear pin is broken and the upper portion of the tool is rotated from the surface, valves 10 are circulating v~lves operated by interior tool hydraulic pres-sure in the hollow core 6, holes 71 com~unicate between the tool core 6 to the inner face of the packer 51 to inflate packer 51 in response to hydraulic pressure P1 in core 6, check valve 58 of the ball-check type admits fluid contents of the well to the interior of the tool as the tool is lowered into the well so that interior pressure in the tool is equalized to the exterior pressure, screen - 10 72 prevents entry of well solids into the interior oF the tool, and 55 represents pressure discs to be blown after the well patch is completed and the upper and lower packers are to be de~lated for withdrawal of the tool from the well. It will be appreciated that additional ball-check valves may be employed in patching wells which have excessive amounts of suspended solid material and that the area of the screen can be varied depending upon the condltions encountered in the well.

In Figures 6 and 7 reference character 60 represents the upper packer, which is fastened at the ends to the steel body of the upper packer assembly, 61 are rupture discs which rupture at pressure P2 to inflate the upper packer (pressure P2 being higher than pressure P1, the pressure at which the lower packer is (;nflated), valves 62 are check valves that equalize the head pressure in the well with the pressure on each side of rupture discs 61 to prevent premature bursting o~ said discs 61, passages 63 lead to the interior face of packer 60 to inflate it. Both packers are shown in the deflated and ln the inflated condition on oposite sides of the tool.

The tool is intended to be operable to patch holes in well casing or tubing without removing the liquid contents of the well.
This is not only for convenience in the field but also due to the fact that disposal of the well contents could pose an environ-mental problem.

~ 3~2~1 With the tool prepared as described in accordance with Figure 1 hereinbefore, it is lowered into the well from tubing string 3 to thP location of the leaking area in the wel1 which must be patched. It is to be emphasized that the patch can be of con-siderable length, e.g., 30 feet, 50 feet or even 100 feet or more.
As the tool descends, ball-check valve 58 opens to equalize interior pressure in the hollow core of the tool 6 with the pres-sure in the well. The hydraulic signals transmitted to the tool from the surface depend upon the differential in pressure within the tool, not the absolute pressure. When the tool has reached the area to be patched, as indicated in Figure 2, pressure in the interior of the tool is increased to P1 and the lower packer is inflated against the casing 32 of the well. This act locks the lower packer assembly against the casing so as to preYent movement and breaks the collar 34, pushing the collar 34 and the first wraps of the lining strip 21 firmly against the inner face of the well casing 32. The tubing string is then rotated from the surface in the direction oppoSite the wrapping directio~n of the liner strip to break the shedr pin 53. The upper portions of the tool are then rotated to unwrap the liner strip 21 against the inner ; face of the casing 32 all the way to the upper packer so as to arrive at the position shown in Figure 3. The resilient nature of the strip material causes 1t to move against the casing as the strip is unwrapped in a manner akin to the uncoiling of a coiled spring. Internal pressure in the tool is then increased to pres-sure P2 to rupture the discs 61 and inflate the upper packer. The inflated upper packer 60 breaks the join of the upper collar 34 and presses it firmly against the casing along with the upper wraps of the liner strip 21. Internal pressure is then raised to P3 to open circulating valves 10 and hot water is c;rculated along the inner face of the liner to set the heat settable resin positioned bet~een the overlapping metal strips 21. ~Ihen suffi-cent time at temperature to set the resin has passed, the internal pressure ls raised to P4 to blow rupture discs 55. This equalizes the internal and external pressures and deflates the packers, whereupon the tool may be removed from the reapired well.

. ~, 2 ~ ~
Bypass passages 67 per~it the circulating liquid to move past the upper pack~r without d~lating it. Alternatively, longitudinal grooves ~ay be provided in the periph~ry o~ the upper pack~r.

Figure 8 depicts a preferr~d pattern ~or s~arting the wraps of liner strip about the tool. Collar 34 is provided with a longitudinal set o~ slots 35 into which the ends of metal strip 21 may be inserted. Between m~tal ~trips 21, strips of plastic screen, such as fly screen, impregnated with liquid epoxy are placed (re~erence character 36) until four strips o~ each descrip-tion have been located. Conveniently, the end of each strip is cut at an angle a~ shown in the drawing. The flap 37, shown more advantageously in ~igures 9 and 10 overlaps the located ends o~
the liner strips 21 and 36 to provide a more secur~ anchor for the strip, and prevent it from becoming unraveled from the tool. The screen matarial can be ~astened to collar 34 using a hot glue gun.
It is very important that the strip be securely fastened to the tool and remain so during descent of the to~l into the well, : becoming detached from th~ teo]. only upon commands from the sur-; face.

Figure g deplcts the pattern o~ the thin strong sheet material from which the collar is made. The pattern is rectan-gular and bears an aligned row o~ slots 38 punched adjacent an edge thereof. A corresponding set of ears 39 parallel to slots 38 is placed at a distance corresponding to the diameter of the collar 34 made when the pattern 40 is rolled into a cylinder.
Slots 35, also shown in Figure ~, are punched adjacent the oppo-site edge of the pattern 40 to hold the lining strip. It will be seen that a flap 37 is formed when pattern 40 is rolled into a cylinder. Ears 39 may be fastened to pattern 40 in breakaway fashion as by spot welding, or may be die-formed into the pattarn.
The ear-and-slot system holds together firmly during w:rapping of the lining strip and descent oE the wrapped tool into the well.
~he force of the expanded paclcers exerted internally upon the collar easily ruptures the collar joins when the proper command is ~.3~2~1 given from the surface and the collar material, being springy, presses firmly against the well casing. The collar material can ~e 0.010 inch thick, aged beryllium copper sheet or strip of high strength.

Figure 10 depicts the pattern 40 of Figure 8 after it haæ
been rolled into the collar. Slots 3~, ear~ 39, Plap 37 and strip-holding slots 35 ars ~hown. Dimples 43 keep collar 34 from slipping on the packer during the wrapping process. A supple-mental set o~ slots 42 and catches 43 cut into pattern 40 may be provided to hold tab 37 tightly to collar 34 as shown in Figure 11 to facilitate passages of th~ collar-wrapped packer through machine ll. Catches 43 are released rrOm the lower collar to permit attachment of the liner strip material to tab 37.

Figures 12A through 12E depict an additional safety feature to prevent loss of the tool down the hole during the wrapping proce s. Each mandrel ~ction can be provided with an annular recess 4a near the top end th~reof. A shoulder 92 surrounds the tool at a location above uppsr c-ullet 28. Shoulder 92 is acti-vated by valve 93 and prevents ~andrel section from moving down even if upper collet 28 is open, as shown in Figure 12B. Shoulder 92 is driven by shaft 94 and spring 95.

It is to be appreciated that the well liner provided in accordance wlth the invention must pass a "gage" test and a pres-sure test a~ter it is formed to demonatrate that it presents no impediment to passage of well tools and that it will prevent seepage of undesireable materials from the interior of the well into the environment. This represents a stringent set of criteria which must be passed. Use oP 0.010 inch thick strip of beryllium copper alloy; with interspersed epoxy provides in fou:r layers essentially the strength oP the original steel casing material and provides far grea~er corrosion resistanae especially to chlorides.

1 31~2~1 Preferably, the h~at settable liquid epoxy is applied to the screen strip material at a point very clsse to ma~drel. A device comprising a tube having a thin slot cut longltudinally therein and having a length of about the width of the screen strip is used as a spreader~ Liquid epoxy is tored ~nder pressure in a dis-cardable container and is led to the spreader by a plastic tube provided with a positive displacement m~ter such as a peristaltic pump, the meter being connected to the scrleen qtrip supply such that the meter turns only when screen strip is actually being wrapped. This positive control pr~vents spillage o~ liquid epoxy when no wrapping is being conducted. Upon completion of the wrapping operation, only the spreader needs to be cleaned. The container and plastic tube can be discarded, a feature of prac-tical advantage in the field. The device is a joint invention of the present inventor and A.C. Hill and will be covered in a separate application.

Claims

1. A method for lining bores comprising:
spiral wrapping a plurality of layers of resilient strip form lining material about a hollow mandrel and mechanically securing said material to said mandrel at the ends of said spiral wrapping;
inserting said mandrel and lining material into a bore to be relined; unwrapping said material from said mandrel so that said material expands until in contact with the bore creating a lining for said bore;
and removing said mandrel.

2. The method of claim 1 wherein said material is wrapped about said mandrel with said layers overlapping each other.

3. The method of claim 1 wherein said strip form lining material is metallic material having a yield strength of at least 50,000 psi.

4. The method of claim 1 wherein said layers of strip material are interleaved with a layer of settable liquid resin.

5. The method of claim 1 wherein said mandrel comprises upper and lower packer assemblies separated by a length of mandrel material corresponding to the desired relining length, said wrapping of strip material is fastened mechanically at the ends thereof to said packer assemblies, said strip material is unfastened from said lower packer assembly by inflating said assembly against the bore wall, said strip material is unwrapped from said mandrel by rotating said mandrel from a point adjacent said inflated lower packer assembly in a direction opposite to the wrapping direction of said strip material and, when said unwrapping has proceeded to said upper packer assembly, inflating said upper packer assembly to detach the upper mechanical fastening therefrom.

6. The method in accordance with claim 5 wherein said strip material is beryllium copper interleaved with screen material impregnated with a heat settable epoxy resin and said resin is set by means of hot water.

7. The method of claim 1 further comprising the step of including a plurality of layers of material impregnated with a heat settable resin between said layers of strip form lining material and heat setting said resin before removing said mandrel.

8. The method of claim 3 wherein the step of heat setting said resin to bond said lining material together is accomplished by:
circulating hot water from said mandrel along the inner face of said lining in said bore.

9. The method of claim 4 wherein collar means are employed to fasten the ends of said wrapping of strip material to said packer assemblies.

10. A mandrel for repairing a bore comprising, a lower packer assembly having a diameter less than said bore capable of expanding in size to the diameter of said bore;

a mandrel connected to one end of said lower packer assembly having a diameter of less than the diameter of said bore;
an upper packer assembly having a diameter less than the diameter of said bore, said upper packer assembly being expandable to a diameter equal to the diameter of said bore;
means for expanding said lower packer assembly prior to the time when said upper packer assembly is expanded; and a locking assembly between said lower packer assembly and said mandrel such that when unlocked, said locking assembly permits said mandrel and upper packer assembly to rotate independent of said lower packer assembly.

11. The mandrel of claim 10 wherein said upper and lower packer assemblies expand by the application of pressure created by pumping a fluid into said mandrel.

12. The mandrel of claim 11 further comprising a circulating valve located between said upper and lower packer assemblies, which when activated, permits said fluid or gas to pass from said mandrel into said bore.

13. The mandrel of claim 10 wherein said circulating valve is activated only when both of said packer assemblies are inflated.

14. The mandrel of claim 10 further comprising a centralizer.

15. The mandrel of claim 11 wherein the inflation of said upper packer assembly is regulated by one or more rupture discs.

16. The mandrel of claim 11 wherein said mandrel further comprises a pressure release mechanism located below said lower packer assembly which when opened depressurizes said mandrel.

17. The mandrel of claim 16 wherein said pressure release mechanism comprises at least one rupture disc.